This is a good point. Just like with anything in engineering understanding the process is more important than just following some steps because you think you should.

When developing software there are many steps before testing even occurs to catch problems, and the earlier you catch problems the better. Coding standards, having requirements, and peer reviews all are important too.

I find tests useful for having a "checklist" of things to do before releasing a new build. In robotics automated tests are especially helpful since there is a lot of code which only happens in certain physical conditions which are hard to recreate manually (i.e. in a low battery condition the robot should do this behavior). But just having the checklist is more important than how you execute it.